Analysis and discussion of different methods of artificial ice-high specimen preparation

Because ice-high foundation soil is widely distributed in permafrost regions,the correct preparation of ice-high specimens is of critical interest in engineering design for foundation stability.Past research has shown that the uniaxial compression strength of ice-high frozen soils changes as the ice or total water content increases; the differences of different methods of specimen preparation are analyzed here and the advantages and disadvantages of them are presented.It is confirmed that the role of crushed ice is significantly different from that of naturally frozen ice in frozen soils,and the size and amount of crushed ice will influence the strength and deformation mechanism of frozen soils.Therefore,it is strongly recommended that when a ice-high specimen is artificially prepared,the ice should be frozen through natural means and not be replaced with crushed ice.     

塔里木西南缘新元古代辉绿岩及玄武岩的地球化学特征：新元古代超大陆（Rodinia）裂解的证据

塔里木西南缘(西昆仑北带)发育新元古代辉绿岩及玄武岩,辉绿岩侵入青白口系而被南华系超覆,玄武岩发育在南华系下部。初步的岩石地球化学研究表明,辉绿岩及玄武岩形成于大陆板内裂解背景,来自EMI型地幔源区。结合对本区格林威尔期造山事件的确定以及新元古代815Ma左右的A型片麻状花岗岩的发现,表明新元古代玄武岩喷发、辉绿岩岩墙侵入等是古塔里木板块作为Rodinia超大陆的一员在新元古代发生裂解的岩浆事件,我们推测超大陆裂解与地幔柱活动有关。     

广东省22个燕山期花岗岩的源区特征及成因：元素及Nd-Sr同位素研究

根据主要元素组成,将所研究的22个广东省燕山期花岗岩分为强过铝花岗岩和弱过铝花岗岩两类,后者又区分出分异和未分异两种。它们总体具有较为相似的微量元素和稀土元素组成,即都是以大离子元素明显富集、Ba,Sr,Nb,Ta,P与Ti呈负异常、Eu亏损为特征,但分异弱过铝花岗岩（包括禾洞、大埔、荷泗、白浆岩体）的Ba、Ti呈负异常和Eu亏损更为明显。强过铝和弱过铝花岗岩的Nd同位素组成区别明显：象头山等6个强过铝花岗岩体具有低的εNd（t）值（-13．4～10．0,平均为-12．1）和较老的Nd模式年龄（1．76—2．08Ga,平均为1．96Ga）,是由成熟度较高的陆壳部分熔融形成;在弱过铝花岗岩中,石背岩体以及禾洞和大埔两个分异岩体具有高的εNa（r）值（-3.6--4．9,平均为-4．4）和年轻的Nd模式年龄（1．23～1.34Ga,平均为1．3Ga）,反映其源区存在一定数量的地幔物质;佛冈等其余12个弱过铝花岗岩体（包括荷泗、白浆2个分异花岗岩）的εNd（t）6t（-12.3～-8．1,平均为-9．7）和Nd模式年龄（1．56～1．94Ga,平均为1．74Ga）都介于上述两类花岗岩之间,但相对较接近于强过铝花岗岩,主要是由成熟度不同程度地低于强过铝花岗岩源区的陆壳变质岩部分熔融形成。广东省燕山期花岗岩主要是在伸展构造及玄武岩底侵条件下,由以沉积变质岩为主的中下陆壳部分熔融形成。